Severe Thunderstorm Watch 308

Issued

May 28, 2012, 12:54 PM CDT (17:54 UTC)

Expired

May 28, 2012, 8:00 PM CDT

In force

7 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

The Green Bay radar (KGRB), 105 km from the middle of the area, began a volume at 17:58 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Two or more tornadoes

20%

One or more EF2 to EF5 tornadoes

5%

Ten or more severe wind reports

40%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

70%

One or more hailstones of 2 inches or more

60%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 938May 28, 12:00 PM CDT
• Mesoscale Discussion 942May 28, 3:58 PM CDT
• Mesoscale Discussion 946May 28, 7:03 PM CDT

880 
WWUS20 KWNS 281756
SEL8
SPC WW 281756
IAZ000-MIZ000-WIZ000-LMZ000-290100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 308
NWS STORM PREDICTION CENTER NORMAN OK
1255 PM CDT MON MAY 28 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

       EXTREME NORTHEAST IOWA
       SOUTHWEST MICHIGAN UPPER PENINSULA
       MUCH OF CENTRAL AND EASTERN WISCONSIN
       LAKE MICHIGAN

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 1255 PM UNTIL
800 PM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95
STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES WEST
NORTHWEST OF IRON MOUNTAIN MICHIGAN TO 25 MILES WEST OF
JANESVILLE WISCONSIN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

DISCUSSION...STRONG ASCENT ACCOMPANYING THE SHORT WAVE TROUGH MOVING
INTO ERN MN AND IA WILL LIKELY AID CONVECTIVE DEVELOPMENT ALONG AND
AHEAD OF A COLD FRONT CURRENTLY SITUATED FROM WRN WI SWWD INTO NERN
IA. AIRMASS AHEAD OF THE FRONT CONTINUES TO DESTABILIZE WITH HEATING
OF THE DAY AND SURFACE-BASED CAPE IS CURRENTLY AROUND 1000 J/KG IN
SOME LOCATIONS. A WIDE ARRAY OF MODEL GUIDANCE INDICATES A
REMARKABLY CONSISTENT SIGNAL FOR THE DEVELOPMENT AND INCREASING
COVERAGE OF DEEP CONVECTION...ESPECIALLY ACROSS NRN AND ERN
WI...THROUGH THIS AFTERNOON. THIS MODEL SIGNAL IS LIKELY A RESULT OF
FAVORABLE LARGE SCALE FORCING FOR ASCENT MOVING INTO THE REGION AND
A LACK OF STRONGER INHIBITION THAN WHAT HAS BEEN IN PLACE IN RECENT
DAYS.
AMBIENT DEEP-LAYER SHEAR OF 40KT WITHIN THE SERN FLANK OF THE LARGE
UPPER LOW TO THE WEST WILL SUPPORT INCREASING STORM ORGANIZATION
WITH SUPERCELLS AND BOWING LINE SEGMENTS POTENTIALLY EVOLVING WITH
TIME. LARGE HAIL AND LOCALLY DAMAGING WINDS MAY ACCOMPANY THE
STRONGER STORMS LATER TODAY.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 24040.


...CARBIN

Severe Thunderstorm Watches in Wisconsin, 2012Severe Thunderstorm Watches in Michigan, 2012Severe Thunderstorm Watches in Iowa, 2012Every severe thunderstorm watch in 2012

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.